1. Field of the Invention
The present invention relates to an image display device, and more particularly, to a method of controlling brightness of a user-selected area for an image display device.
2. Discussion of the Related Art
Typical computer-related display systems use a Cathode Ray Tube (CRT) monitor for displaying various types of data including video and text. For displaying video data such as motion pictures, graphics, and photographs on the CRT monitor, a reasonably high level of luminosity is often required because far more colors are used to provide realistic shading and variations in color. The increase in the luminosity range of the video data on the CRT monitor makes the video image richer in contrast and brightness, improving the perceptual quality of the image.
However, compared to TV systems, the existing computer-related display systems that include a CRT monitor usually do not provide enough luminosity when displaying the mentioned video data. For example, when a video signal for an ordinary TV system (e.g., a broadcasting video signal or any other signal for display on a TV screen) is displayed on one of the oridinary CRT monitors, the brightness of the displayed image is typically too low and the image is too dark and shadowy. This is because the brightness parameters of the existing computer-related display systems are usually much less than those of the TV systems.
In order to obviate the problem set above, it would be highly desirable to have a method of greatly increasing the luminosity level of a user-selected area of the CRT screen while retaining the luminosity of the all other areas at a relatively lower level. In this way, the perceptual image-quality of the user-selected area can be greatly improved without increasing the brightness of the whole screen, providing a desirable solution to the above-mentioned problem.